Apparatus and methods for directional delivery of laser energy

ABSTRACT

In some embodiments, without limitation, the invention comprises a catheter having an elongated housing with a channel disposed therein. A laser delivery member is movable and at least partially disposed within the channel. A ramp is disposed within the housing at an angle to its central axis and proximate to its distal end. The ramp is adapted to move the distal end of the laser delivery member outwardly from the central axis of the housing. A guidewire biases the distal end of the laser delivery member generally inwardly toward the central axis of the housing. In some embodiments, without limitation, the offset of the central axis of the tip of the laser delivery member from the central axis of the housing is determined by adjusting the extent to which the laser delivery member travels on the ramp, and disposition of the laser delivery member on the guidewire maintains the offset tip substantially parallel to the central axis of the housing. Thus, in accordance with the invention, the distal end of the laser delivery member may be biased in a desired direction or offset, permitting ablation of an area larger than the area of the distal end of the catheter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser.No. 60/611,191 filed Sep. 17, 2004, which is hereby incorporated byreference in its entirety.

TECHNICAL FIELD

The embodiments described herein are generally directed to improvedapparatus and methods for the delivery of laser energy, includingwithout limitation, to a laser delivery catheter.

BACKGROUND

Arteries are the primary blood vessels that are responsible forproviding blood and oxygen to the heart muscle. Arterial disease occurswhen arteries become narrowed or blocked by a buildup of plaque (as someexamples, atherosclerotic plaque or other deposits). When the blockageis severe, the flow of blood and oxygen to the heart muscle is reduced,causing chest pain. Arterial blockage by clots formed in a human bodymay be relieved in a number of traditional ways. Drug therapy, includingnitrates, beta-blockers, and peripheral vasodilatator drugs to dilatethe arteries or thrombolytic drugs to dissolve the clot, can beeffective. If drug treatment fails, angioplasty may be used to reform orremove the atherosclerotic plaque or other deposits in the artery.

Traditional balloon angioplasty is sometimes used to address theblockage by inserting a narrow, flexible tube having a balloon into anartery in the arm or leg. The blocked area in the artery can bestretched apart by passing the balloon to the desired treatment site andgently inflating it a certain degree. In the event drug therapy isineffective or angioplasty is too risky (often introduction of a balloonin an occluded artery can cause portions of the atherosclerotic materialto become dislodged which may cause a total blockage at a pointdownstream of the subject occlusion thereby requiring emergencyprocedures), the procedure known as excimer laser angioplasty may beindicated.

Excimer laser angioplasty procedure is similar in some respects toconventional coronary balloon angioplasty. A narrow, flexible tube, thelaser catheter, is inserted into an artery in the arm or leg. The lasercatheter contains one or more optical fibers, which can transmit laserenergy. The laser catheter is then advanced inside the artery to thetargeted obstruction at the desired treatment site. After the lasercatheter has been positioned, the laser is energized to “remove” theobstruction.

In many procedures, the lesion is often engaged similar to conventionalballoon angioplasty by crossing the blockage with a guidewire. The lasercatheter's thin, flexible optical fibers facilitate the desiredpositioning and alignment of the catheter. Using the excimer laser, theclinician performs a controlled blockage removal by sending bursts ofultraviolet light through the catheter and against the blockage, aprocess called “ablation.” The catheter is then slowly advanced throughthe blockage reopening the artery. If there are multiple blockages, thecatheter is advanced to the next blockage site and the above step isrepeated. When the indicated blockages appear to be cleared, thecatheter is withdrawn.

However, due to the configuration of the optical fibers in most priorart laser catheters, the clinician is able to ablate only material thatis typically directly in front of the distal end of the catheter. Thus,the debulked tissue area is limited to an area approximately the size ofthe optical fiber area at the distal end of the catheter. Typically,follow-up angioplasty is recommended.

Thus, it would be desirable to provide an apparatus and methods thatcould bias the distal end of the laser catheter in a desired directionto enable the clinician to ablate an area larger than the area of thedistal end of the catheter. Furthermore, because plaque may be eccentricin a blood vessel and require directional control to adequately ablatethe target area, it would be advantageous to provide an apparatus thatis sufficiently flexible to travel and rotate around the target area sothat the clinician may control the area to be ablated.

SUMMARY

In accordance with some embodiments, without limitation, the inventioncomprises a catheter having an elongated housing including a centralaxis between a first proximal end and a first distal end. The housinghas a channel disposed between the first proximal end and the firstdistal end in communication with a cavity disposed proximate the firstdistal end. A laser delivery member is movable and at least partiallydisposed within the channel having a second proximal end and a seconddistal end. A ramp is disposed at an angle to the central axis andproximate the first distal end of the elongated housing within thecavity. The ramp is in communication with the channel and is adapted tomove the second distal end of the laser delivery member outwardly fromthe central axis of the elongated member. A guidewire is in mechanicalcommunication with both the laser delivery member and the elongatedhousing. The guidewire is adapted to bias the second distal end of thelaser delivery member generally inwardly toward the central axis of thehousing. In some embodiments, without limitation, the ramp is used todetermine the offset of the central axis of the tip of the laserdelivery member from the central axis of the housing, while keeping theaxes substantially parallel, by adjusting the extent to which the laserdelivery member travels on the ramp, and the disposition of the laserdelivery member on the guidewire maintains the offset tip substantiallyparallel to the central axis of the housing. Methods of using same arealso disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and inventive aspects of the present invention will becomemore apparent upon reading the following detailed description, claims,and drawings, of which the following is a brief description:

FIG. 1 is perspective elevated view of a catheter according to oneembodiment;

FIG. 2 is an exploded perspective view of a cavity of FIG. 1;

FIG. 3 is an exploded perspective view of FIG. 1 showing one embodimentof a ramp;

FIG. 4 is an exploded perspective view of FIG. 1 showing a ramp, a laserdelivery member, and a guidewire;

FIG. 5 is a perspective elevated view of a first embodiment of a supportstructure;

FIG. 6 is a top plan view of FIG. 5;

FIG. 7 is a side plan view of FIG. 5;

FIG. 8 is a top plan view of a second embodiment of a support structure;

FIG. 9 is a side plan view of FIG. 8;

FIG. 10 is a perspective elevated view of a third embodiment of asupport structure;

FIG. 11 is a top plan view of FIG. 10;

FIG. 12 is a perspective elevated view of a fourth embodiment of asupport structure;

FIG. 13 is a perspective elevated view of a fifth embodiment of asupport structure;

FIG. 14 is a perspective elevated view of a sixth embodiment of asupport structure;

FIG. 15 is a top plan view of a seventh embodiment of a supportstructure; and

FIG. 16 is a perspective elevated view of FIG. 15.

DETAILED DESCRIPTION

Referring now to the drawings, illustrative embodiments are shown indetail. Although the drawings represent some embodiments, the drawingsare not necessarily to scale and certain features may be exaggerated tobetter illustrate and explain an innovative aspect of an embodiment.Further, the embodiments described herein are not intended to beexhaustive or otherwise limit or restrict the embodiments of theinvention to the precise form and configuration shown in the drawingsand disclosed in the following detailed description.

Referring now to FIGS. 1-4, a catheter 10 is shown having an elongatedhousing 12. The elongated housing 12 includes a central axis between afirst proximal end 14 and a first distal end 16. A cavity 18 is locatedproximate to the first distal end 16 of elongated housing 12 having aramp 20 at an angle to the central axis of the housing 12. The angle ofthe ramp 20 may but need not be the same over the length of the ramp. Insome preferred embodiments, without limiting the scope of the invention,the housing includes a tapering end 30 and a guide wire aperture 32capable of accepting the guidewire 28. A laser delivery member 22comprising one or more optical fibers capable of transmitting lightenergy is disposed within a channel 26 of the housing 12 having a secondproximal end (not shown) and a second distal end 24 movable therein. Insome embodiments, without limitation, the laser delivery member 22 maybe in mechanical communication with a guidewire 28 as further discussedbelow.

The guidewire 28 is threaded through a needle (not shown) into theartery and the needle is removed. The guidewire is advanced to or nearthe treatment site and may be inserted at its distal end into or acrossthe lesion to be treated, as desired. The guidewire 28 serves as atracking guide for the housing 12 and laser delivery member 22 to runon. Guidewires for such uses are known in the art and may comprise thosewith diameters between about 0.010 and 0.06 inches, with 0.014 and 0.018inches diameter being typical sizes for artery applications. Theguidewires may have bendable tips of coiled wire or plastic and a morerigid shaft of tapered ground stainless steel or other suitable materialfor push and torque transmission. The housing 12 and laser deliverymember 22 are introduced coaxially, either sequentially orsimultaneously, onto the guidewire 28 and advanced to a target area asfurther discussed below.

In some embodiments, without limitation, the housing 12 is introducedonto the guidewire 28 that has been inserted into the patient, and thehousing is advanced to or near the treatment site such that portions ofthe guidewire 28 are disposed at least initially within the guide wireaperture 32, tapering end 30, and channel 26 of the housing. The laserdelivery member 22 is then introduced onto the guidewire 28 so disposedwithin the catheter 10. The laser delivery member 22 is then advancedalong the guidewire 28 such that the distal end 24 of the laser deliverymember 22 becomes supported by the ramp 20 and oriented within thecavity 18 at any angle between 1 degree and 90 degrees in relation tothe central axis of the housing 12, as desired by the user. Laser energyis then applied to the treatment site according to methods and protocolsknown to those of ordinary skill in the art. In some embodiments,without limiting the scope of the invention, in conjunction with theapplication of laser energy, the position of the laser delivery member22 may optionally be varied by the user by moving the member 22proximally or distally in order to adjust the angle of disposition ofits distal end 24. Optionally, the offset of the central axis of the tipof the laser delivery member 22 from the central axis of the housing 12may be varied by adjusting the distance that the delivery member 22travels on the ramp 20 while keeping the central axis of the tipsubstantially parallel to the central axis of the housing 12. Inaddition, the catheter 10 containing the laser delivery member 22 mayoptionally be rotated along its central axis during the laser treatmentand thereby apply laser energy to areas of the treatment site within thearc of the rotation. Optionally, the guidewire 28 may be withdrawnbefore application of laser energy and after the laser delivery member22 has been introduced via the guidewire 28 into the channel 26 of thehousing 12.

The elongated housing 12 is an elongated structure having a lumen orchannel 26 large enough to accommodate the laser delivery member 22 andguidewire 28. The channel 26 extends the entire length of the housing 12from the first proximal end 14 to the first distal end 16. Optionally,in some embodiments, the channel 26 may extend only to the ramp 20.Various control mechanisms including electrical, optical, and mechanicalcontrol mechanisms may be employed with the housing 12 permitting thecatheter to be specifically directed to a target area (not shown) withinthe blood vessel. One embodiment of the housing includes a tapering end30 and a guide wire aperture 32 capable of accepting the guidewire 28.The housing 12 may be made from any rigid, semi-flexible, or flexiblematerial including a combination thereof made from a material includingmetal, plastic, rubber, and the like. Round or flat metal ribbon wiremay be embedded within the material, inserted through the cavity 18, ordisposed at the first distal end 16 to add stability to the housing 12at the first distal end 16. The length of the housing 12 may be variedas desired. The housing 12 may be one piece or have a plurality ofsections including a support structure section at the first distal end16 as discussed further below. The distal end 16 of the housing 12 mayinclude a non-traumatic polymer tip separate or integrated into thehousing 12. This allows the forces seen in bending to be dissipatedthroughout the structure, reducing stress risers that could causefailure. The housing 12 may also include at least one wire disposedwithin the channel 26 to add robustness to the housing 12. The channel26 is in communication with cavity 18 and wire aperture 32. The channel26 is open to the exterior of the housing 12 through the cavity 18.

The ramp 20 is disposed within cavity 18 and is configured to projectthe laser delivery member 22 outwardly at various determinable angles.Optionally, the ramp 20 is used to determine the offset of the centralaxis of the tip of the laser delivery member 22 from the central axis ofthe housing 20, while keeping the axes substantially parallel, byadjusting the extent to which the laser delivery member 22 travels onthe ramp 20. In some embodiments without limitation, the disposition ofthe laser delivery member 22 on the guidewire 28 maintains the offsettip substantially parallel to the central axis of the housing 12. Insome embodiments, without limitation, the angle of lateral deviation ofthe ramp 20 from central axis of the housing 12 will vary in range asdesired from one (1) degree to ninety (90) degrees, more usually in therange from thirty (30) degrees to sixty-five (65) degrees. By employingramp 20 having different exit angles from the associated channel 26,different angles and/or offsets may be selected for treating a targetarea after the catheter 10 has been located within a patient. In someembodiments, without limitation, the ramp 20 may be adjustable, as oneexample only, by inflation of a balloon, and/or the ramp 20 may beslidable to allow varying degrees of offset.

The ramp 20 may be a built-up feature within the channel 26 of thehousing 12 and may be located anywhere along the longitudinal length ofthe housing 12, but preferably at or within about 3 cm from the firstdistal end 16 of the housing 12. The ramp 20 may be formed or fused tothe internal wall of the housing 12 and made from metal, plastic,rubber, and the like. In one embodiment, the ramp length (RL) isgenerally 1 cm. However, the ramp length (RL) may also be varied.

The first distal end 16 of the housing 12 may be formed from plastic,metal, or any combination thereof. When metal is used, materials must beselected to provide appropriate flexibility without producing failuresince the cavity 18 tends to reduce the structural integrity of someportions of the housing 12. Thus, in some embodiments, the first distalend 16 comprises a shape memory alloy, as one example only,nickel-titanium alloy. In other embodiments, without limitation, thefirst distal end 16 may comprise a stent-like structure proximal,distal, within, or a combination of such proximate the cavity 18. Thestent-like structure may be made from at least one of stainless steel,cobalt-chromium, nickel titanium, and the like.

An alternative embodiment of the housing 12 comprises having at leastone section at the first distal end 16. A first embodiment of a supportstructure is support member 34 as shown in FIGS. 5-7. The support member34 may be used to support the first distal end 16 while providingflexibility without producing failure. The first distal end 16 of thehousing 12 may otherwise experience limited torsional and bendingstrength of the area around the cavity 18 specifically traversing bendshaving a radius of about 0.75 inches. The support member 34 assists inwithstanding the torsional and bending forces when traversing bends ofabout 0.75 inches, while maintaining aspects of both integrity andfunctionality. In some embodiments, without limitation, support member34 reinforces the area around the cavity 18 at the first distal end 16with struts 36 forming a stent-like pattern 38. Support member 34 isformed from metal, plastic, or combinations thereof, and is at leastpartially axially disposed around the wall of the first distal end 16 ofthe housing 12. The housing 12 may be one longitudinal piece or have aplurality of sections including the support structure as described abovedisposed at the first distal end 16 of the housing 12. Other embodimentsof the support structure include a marker band proximate the firstdistal end 16 of the housing 12 and radiopaque markers at variousintervals along the ramp 20 to demarcate acceptable ramp 20 positionsfor the catheter 10. As one example only, a user may place a catheter ata first mark on the ramp to increase the offset for ablation to 1 mm. Asecond mark might equal a 1.5 mm offset. This way the support structuremay be used progressively, as one example only, as a progressiveatherectomy tool. Additional embodiments having generally similarbenefits may also be used, as further discussed below.

Referring to FIGS. 8 and 9, a second embodiment of a support structureis shown as second support member 40 having a spring-like geometry 42.The support member 40 may be used to support the first distal end 16while providing flexibility without producing failure. The secondsupport member 40 acts as a backbone for the first distal end 16 of thehousing 12. The spring-like geometry 42 permits flexing without causingfailure. The height H of the spring-like geometry 42 may be of anyheight but is preferably below the centerline of the second supportmember 40. The ramp 20 may be molded over the spring like geometry 42including having a top coat (not shown).

Referring to FIGS. 10 and 11, a third embodiment of a support structureis shown as a third support member 44. The support member 44 may be usedto support the first distal end 16 while providing flexibility withoutproducing failure. The third support member 44 provides variablestiffness along the length of the member 44. Member 44 is the most rigidat rib 46 and most flexible at rib 48. This flexibility is accomplishedby having the ribs increase in width W and distance D in addition todecreasing the side of a beam 50 as shown in FIG. 11. Beam 50 tapersfrom a first wide beam width BW1 to a narrower beam width BW2. A tip 52having a tip length TL disposed at the distal end support member 44functions to provide support for the first distal end 16 of the housing12 while allowing additional flexibility. The ramp 20 may be molded overthe spring-like geometry 42 including having a top coat (not shown). Thesupport member length L may be varied depending on user requirementsincluding varying the tip length TL.

FIG. 12 shows a fourth embodiment of a support structure as fourthsupport member 54 disposed at the first distal end 16 of the housing 12.The support member 54 may be used to support the first distal end 16while providing flexibility without producing failure. Support member 54includes a rigid body 56 and a variably rigid base 58 extending from thebody 56. Body 56 includes an aperture 57 in communication with channel26. The base 58 may be elastomeric having the greatest flexibility atdistal end 60. The ramp 20 may be molded over the base 58 includinghaving a top coat (not shown). The support member base length BL may bevaried according to user requirements.

FIG. 13 shows a fifth embodiment of a support structure as fifth supportmember 62. The support member 62 includes a rigid body 64 having aflexible tapered nose portion 66. At least the nose portion 66 may becomprised of elastomeric material, as one example only, Rebax 55Davailable from Arkema. The body 64 is configured to communicate with thefirst distal end 16 of the housing 12. An aperture 68 is disposed withinbody 64 in communication with channel 26 of the housing 12 and isconfigured to accommodate both the laser delivery member 22 andguidewire 28. Aperture 68 is also in communication with the nose widow69. The nose window 69 of the nose portion 66 includes a nose ramp 70configured to project the laser delivery member 22 outwardly at variouspredetermined angles. Optionally, the ramp 20 is used to determine theoffset of the central axis of the tip of the laser delivery member 22from the central axis of the housing 20, while keeping the axessubstantially parallel, by adjusting the extent to which the laserdelivery member 22 travels on the ramp 20. In some embodiments withoutlimitation, the disposition of the laser delivery member 22 on theguidewire 28 maintains the offset tip substantially parallel to thecentral axis of the housing 12. Usually, the angle of lateral deviationof the ramp 20 from the housing 12 will vary in range as desired fromone (1) degree to ninety (90) degrees, more usually in the range fromthirty (30) degrees to sixty-five (65) degrees. The nose portion alsoincludes a nose channel 72 and a nose guidewire aperture 74. Theguidewire 28 disposed within and in mechanical communication the laserdelivery member 22 extends outwardly from the second distal end 24 ofthe laser delivery member 22 and is guided through the nose channel 72and extending out the guidewire aperture 74. Both the nose channel 72and guidewire aperture 74 provide securement for the guidewire 28 sothat the guidewire 28 may properly bias the second distal end 24 of thelaser delivery member 22 generally inwardly toward the central axis ofthe body 64.

FIG. 14 shows a sixth embodiment of a support structure as sixth supportmember 80. The support member 80 may be used to support the first distalend 16 while providing flexibility without producing failure. Supportmember 80 includes a rigid body 82 and at least two variably rigid legs84 extending from the body 82. Body 82 includes an aperture 86 incommunication with the channel 26. The body 82 may be elastomeric havingthe greatest flexibility at distal end 88. The legs 84 may be of anyshape extending from the body 82. The ramp 20 may be molded over thelegs 84 including having a top coat (not shown). The support member leglength LL may be varied depending on user requirements.

FIGS. 15 and 16 show a seventh embodiment of a support structure asseventh support member 90. The support member 90 may be used to supportthe first distal end 16 while providing flexibility without producingfailure. The first distal end 16 of the housing 12 may otherwiseexperience limited torsional and bending strength of the area around thecavity 18 specifically traversing bends having a radius of about 0.75inches. The support member 90 assists in withstanding the torsional andbending forces when traversing bends of about 0.75 inches whilemaintaining both integrity and functionality. Support member 90reinforces the area around the cavity 18 at the first distal end 16 witha braid 92 forming a stent-like pattern 94. Support member 90 is formedfrom metal or plastic and is at least partially axially disposed aroundthe wall of the first distal end 16 of the housing 12. The housing 12may be one longitudinal piece or have a plurality of sections includingthe support structure as described above disposed at the first distalend 16 of the housing 12. Support member 90 includes a rigid body 92 anda variably rigid base 94 forming the stent-like pattern 94 extendingfrom the body 92. Body 92 includes an aperture 96 in communication withchannel 26. The base 94 may be elastomeric having the greatestflexibility at distal end 98. A tip 100 having a tip length TL disposedat the distal end support member 90 functions to provide support for thefirst distal end 16 of the housing 12 while allowing additionalflexibility. The ramp 20 may be molded over the base 94 including havinga top coat (not shown). The support member stent-like length SL may bevaried depending on user requirements.

In operation, once the guidewire 28 is in place, or as it is beingpositioned, the housing 12 is inserted. This housing 12 has a centralchannel 26, which may include the laser delivery member 22 and guidewire28. The housing 12 and the laser delivery member 22 are advanced throughthe guidewire into the desired target area. Therefore, the guidewire 28is in mechanical communication with both the laser delivery member 22and the elongated housing 12. However, the housing 12 may be advancedprior to inserting the laser delivery member 22. As the laser deliverymember 22 approaches the ramp 20, it is biased in an outwardly directionthrough the cavity 18. The further the laser delivery member 22 isadvanced, the more it projects outwardly from the cavity 18 at the firstdistal end 16 of the housing 12. In some embodiments, withoutlimitation, the guidewire 28 disposed within the laser delivery member22 biases the second distal end 24 of the laser delivery member 22inwardly providing a travel path and forcing the second distal end 24 toface forward along the guidewire 28 and generally parallel to thecenterline of the housing 12. Otherwise, the second distal end 24 of thelaser delivery member 22 would continue along the ramp 20 furtherprojecting away from the centerline of the housing 12 and would not be“attacking” the target area in front of the catheter 10 as desired.

The preceding description has been presented only to illustrate anddescribe exemplary embodiments of the methods and systems of the presentinvention. It is not intended to be exhaustive or to limit the inventionto any precise form disclosed. It will be understood by those skilled inthe art that various changes may be made and equivalents may besubstituted for elements thereof without departing from the scope of theinvention. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the inventionwithout departing from the essential scope. Therefore, it is intendedthat the invention not be limited to the particular embodiment disclosedas the best mode contemplated for carrying out this invention, but thatthe invention will include all embodiments falling within the scope ofthe claims. The invention may be practiced otherwise than isspecifically explained and illustrated without departing from its spiritor scope.

1. A catheter comprising: an elongated housing having a central axisbetween a first proximal end and a first distal end, said housing havinga channel disposed at least part way between said first proximal end andsaid first distal end, the elongated housing further including a tip atthe first distal end, the tip having a first guidewire lumen; a laserdelivery member having a second proximal end and a second distal end andcomprising at least one optical fiber, said laser member being at leastpartially disposed within said channel and movable therein, wherein thelaser delivery member further includes a second guidewire lumen; acavity being disposed proximate said first distal end of said elongatedhousing and in communication with said channel; a ramp proximate saidfirst distal end of said elongated housing, said ramp being incommunication with said channel and having an inclining proximal sectionand an apex section, said ramp adapted to move said second distal end ofsaid laser delivery member laterally away from said central axis of saidelongated member when the distal end of the laser delivery member is onthe ramp; and a guidewire extending through the second guidewire lumenof the laser delivery member, over the ramp and through the firstguidewire lumen at the tip of the elongated housing, said guidewirebeing adapted to position said second distal end of said laser deliverymember laterally away from and generally parallel to said central axisas the distal end of the laser delivery member is at or beyond the apexsection of the ramp.
 2. The catheter of claim 1, wherein said elongatedhousing is formed from a flexible material.
 3. The catheter of claim 2,wherein said flexible material is sufficiently flexible to permit saidhousing to travel contralaterally within the vasculature of a mammal. 4.The catheter of claim 1, wherein said elongated housing includes abraided pattern along at least a portion of said housing.
 5. Thecatheter of claim 1, wherein said elongated hosing includes a braidedpattern along at least one half of a length of said housing.
 6. Thecatheter of claim 1, wherein said elongated housing includes a round orflat metal ribbon wire embedded within said housing.
 7. The catheter ofclaim 1, wherein said elongated housing includes a wire braid disposedproximate said first distal end.
 8. The catheter of claim 1, whereinsaid elongated housing includes at least one wire disposed within saidhousing.
 9. The catheter of claim 1, wherein said elongated housingincludes a polymer tip disposed at said first distal end separate fromor integrated into said housing.
 10. The catheter of claim 1, whereinsaid elongated housing includes a stent-like structure disposedproximate at least one of said distal end, said proximal end, andtherebetween.
 11. The catheter of claim 10, wherein said stent-likestructure is formed from one of stainless steel, cobalt-chromium, andnickel titanium or any combination thereof.
 12. The catheter of claim 1,wherein said ramp is inflatable.
 13. The catheter of claim 1, whereinsaid ramp is formed into an internal wall of said housing.
 14. Thecatheter of claim 1, wherein said ramp is formed from one of a metal,plastic, and rubber.
 15. The catheter of claim 1, wherein said rampincludes a marker band disposed along said ramp.
 16. The catheter ofclaim 1, wherein said ramp includes at least one radiopaque markerdisposed at a predetermined location along a longitudinal length of saidramp.
 17. The catheter of claim 1, further comprising a supportstructure disposed at said first distal end of said housing.
 18. Thecatheter of claim 17, wherein said support structure is integrated withsaid housing proximate said first distal end.
 19. The catheter of claim17, wherein said support structure includes an aperture in communicationwith said channel.
 20. The catheter of claim 17, wherein said supportstructure includes a stent-like or coiled form.
 21. The catheter ofclaim 17, wherein said support structure is progressively more flexiblefrom a support structure proximal end to a support structure distal end.22. The catheter of claim 17, wherein said support structure includes asurface comprising at least a portion having a stent-like pattern. 23.The catheter of claim 17, wherein said support structure includes saidramp molded into a surface of said support structure.
 24. The catheterof claim 17, wherein said support structure supports said first distalend of said housing.
 25. A catheter support structure comprising: ahousing having a proximal end, a distal end, a central axis, a proximallumen, a distal lumen, and an aperture disposed at least partiallywithin said housing so as to be between the proximal lumen and thedistal lumen, wherein the proximal lumen and the distal lumen areadapted to hold a guidewire; a ramp having an inclining proximal sectionand an apex section, said ramp being positioned between the proximallumen and the distal lumen such that the apex is positioned laterallyaway from the proximal lumen and the distal lumen, the ramp being incommunication with said aperture and adapted to move a distal end of alaser delivery member laterally away from said central axis afterpassing through the proximal lumen over the guidewire, and to positionthe distal end of the laser delivery member laterally away from andgenerally parallel to the central axis as the distal end of the laserdelivery member is at or beyond the apex section of the ramp.
 26. Thecatheter support structure of claim 25, wherein said ramp is molded intoa surface of said housing.
 27. The catheter support structure of claim25, wherein said ramp is inflatable.
 28. The catheter support structureof claim 25, wherein said ramp is formed into an internal wall of saidhousing.
 29. The catheter support structure of claim 25, wherein saidramp is formed from one of a metal, plastic, and rubber, or anycombination thereof.
 30. The catheter support structure of claim 25,wherein said ramp includes a marker band disposed along said ramp. 31.The catheter support structure of claim 25, wherein said ramp includesat least one radiopaque marker disposed at a predetermined locationalong a longitudinal length of said ramp.
 32. The catheter supportstructure of claim 25, wherein the distal lumen is adapted to receive aguidewire, said guidewire being adapted to bias the distal end of saidlaser delivery member generally inwardly toward said central axis. 33.The catheter support structure of claim 25, wherein said cathetersupport structure is integrated with a catheter housing.
 34. Thecatheter support structure of claim 25, further comprising at least oneflexible structure disposed proximate said distal end of said housinghaving a proximal end and a distal end, said at least one flexiblestructure is increasingly flexible from said proximal end to said distalend, and wherein said at least one flexible structure includes astent-like or coiled form.
 35. A catheter system, comprising: a cathetersheath comprising a sheath body having a proximal end, a distal end, aproximal lumen, a distal lumen, a ramp disposed between the proximallumen and the distal lumen, and an opening proximal to the ramp, whereinthe ramp has an inclining proximal section and an apex section; a laserdelivery member having a proximal end and a distal end, wherein thelaser delivery member is movable within the proximal lumen of thecatheter sheath; a guidewire adapted to extend through the proximallumen and the distal lumen of the catheter sheath such that it passesover the ramp; wherein the laser delivery member includes a guidewirelumen to permit the distal end of the laser delivery member to trackalong the guidewire as it moves along the ramp, with the guidewireadapted to position the distal end of the laser delivery memberlaterally away from and generally parallel to the central axis as thedistal end of the laser delivery member is at or beyond the apex of theramp.